Allogeneic cell therapy is an important curative therapy for several types of malignancies and viral diseases. Allogeneic cell therapy involves the infusion or transplant of cells to a patient, whereby the infused or transplanted cells are derived from a donor other than the patient. Types of allogeneic donors that have been utilized for allogeneic cell therapy protocols include: HLA-matched siblings, matched unrelated donors, partially matched family member donors, related umbilical cord blood donors, and unrelated umbilical cord blood donors. The allogeneic donor cells are usually obtained by bone marrow harvest, collection of peripheral blood or collection of placental cord blood at birth. This requirement for a matched donor is a major limitation of allogeneic cell therapy protocols. It is an object of this invention to provide a method of allogeneic cell therapy that is effective without the requirement for HLA matching.
Allogeneic cell therapy methods have been practiced in the bone marrow transplant (BMT) setting for over 30 years (Kai and Hara 2003). These methods involve treatment of patients with high dose (myeloablative) chemotherapy and/or radiation. This myeloablative conditioning results in destruction of the bone marrow leading to the loss of a functioning immune system. Thus, these patients must be “rescued” by allogeneic cell transplant to replace the destroyed bone marrow and restore immunity.
The ability of myeloablative conditioning followed by allogeneic BMT or stem cell transplantation (SCT) to cure certain hematological malignancies is widely recognized. The anti-tumor effect mediated by the allogeneic cell transplant is known as the graft vs. tumor (GVT) effect (also called the graft vs. leukemia effect and the graft vs. malignancy effect and the graft vs. myeloma effect). GVT activity after allogeneic cell therapy is known to be effective in treating several cancers, including myeloid leukemias (Gale and Champlin 1984), lymphoid leukemias (Rondon, Giralt et al. 1996, multiple myeloma {Tricot, 1996 #2730) and breast cancer (Eibl, Schwaighofer et al. 1996).
However, allogeneic BMT has a treatment related mortality of 30-35% (Frassoni, Labopin et al. 1996). The high risk of transplant related mortality has limited the use of this treatment mostly to otherwise healthy patients with hematological malignancies. It is an object of this invention to significantly reduce or eliminate the treatment related mortality of allogeneic cell therapy in order to make the treatment available to a broader spectrum of patients and disease indications.
The GVT effect was discovered when it was observed that relapse rates were significantly lower in patients that received an allogeneic BMT compared to patients that received an autologous BMT. This led to the discovery that the reduced relapse rate was mediated by anti-tumor reactions of lymphocytes contained in the allograft (GVT effect) (Weiden, Sullivan et al. 1981).
Direct evidence of the power of the GVT effect was first provided when patients with chronic myelogenous leukemia (CML) who relapsed after allogeneic BMT were put in complete remission after an infusion of allogeneic lymphocytes (a procedure known as Donor Lymphocyte Infusion or DLI). DLI treatment has since been shown to frequently cause complete remissions in relapsed cancer patients following allogeneic BMT, despite complete resistance of such tumor cells to maximally tolerated doses of chemotherapy/radiation (Slavin, Naparstek et al. 1995; Slavin, Naparstek et al. 1996; Slavin, Naparstek et al. 1996) (See also Slavin U.S. Pat. Nos. 5,843,435 and 6,143,292).
The observation that DLI treatment alone, without chemotherapy, could have an anti-tumor effect has led to a paradigm shift in the treatment of malignancy. A new generation of therapies has emerged where the focus is on the GVT effect, rather than the cytotoxic effect of chemotherapy/radiation. This new generation of allogeneic cell therapy protocols is known as a “Mini-Transplant” (for example, see U.S. Pat. No. 6,544,787 issued to Slavin and U.S. Pat. No. 6,558,662 issued to Sykes, et al.).
Mini-Transplant procedures involve a first round of low dose, non-myeloablative chemotherapy conditioning of a patient. The low dose chemotherapy conditioning is not provided for the purpose of tumor reduction, but rather is designed to only weaken the immune system enough to prevent rejection of an allogeneic donor cell infusion. Conditioned patients are infused with non-manipulated allogeneic lymphocytes or stem cells which engraft in the patients and subsequently mediate a GVT effect.
Patients with successfully engrafted allogeneic cells develop immune systems which are partially of self origin and partially of the allogeneic graft origin. Patients in this immunological state are known as “chimeras”. The conditioning regimen enabling chimera formation usually includes administration of one or more chemotherapy conditioning agents, such as purine analogs like fiudarabine, alkylating agents such as busulfan and/or cyclophosphamide, and/or anti-leukocyte globulins (see U.S. Pat. No. 6,544,787 issued to Slavin).
These Mini-Transplant protocols have proven to be very effective in the treatment of hematological malignancies and are less toxic than the high dose myeloablative regimens (Champlin, Khouri et al. 1999; Champlin, van Besien et al. 2000); (Grigg, Bardy et al. 1999); (Slavin, Nagler et al. 2001; Slavin, Or et al. 2001). Mini-Transplants have also been shown to be effective in chemotherapy resistant metastatic disease (Childs, Chernoff et al. 2000; Childs 2000; Childs and Barrett 2002; Childs 2002).
While the GVT effect has been described as the most powerful and effective anti-tumor mechanism ever observed in the treatment of human malignancies (van Besien, Thall et al. 1997) (Eibl, Schwaighofer et al. 1996) (Deno, Rondon et al. 1998), the clinical application of GVT is still severely limited due to the toxicity associated with allogeneic cell infusions. The major complication of allogeneic cell therapy is the condition known as graft vs. host (GVH) disease. GVH disease occurs when donor T-cells react against antigens on normal host cells causing target organ damage, which often leads to death. The principal target organs of GVH disease are the immune system, skin, liver and intestine.
There is an urgent need to develop methods to separate the beneficial GVT effect from the detrimental GVH effect in allogeneic cell therapy. However, this has proven to be very difficult, as it appears that GVT and GVH are intimately related processes, with the same donor T-cells responsible for both effects. It is an object of this invention to describe an allogeneic cell therapy method which provides an anti-tumor effect without the toxicity associated with GVH disease.
GVH disease occurs secondary to mismatches between histocompatibility antigens (HLA) between the donor and the recipient. Attempts to perform allogeneic BMT between strongly HLA-mismatched donor-recipient pairs have been associated with a prohibitively high incidence of severe GVH disease and failure of the allogeneic cell infusions to engraft. Therefore, allogeneic cell therapy normally requires matching of HLA antigens between donor and recipient. However despite matching of HLA identity, substantial numbers of patients still develop GVH disease, presumably due to differences in minor HLA antigens.
The requirement for an HLA matched donor severely limits the application of allogeneic cell therapy. Only approximately one of every three patients has an HLA-matched sibling or can find a phenotypically matched unrelated donor, and therefore the majority of patients do not have the option of allogeneic cell therapy. Furthermore, a large fraction of cancers, including leukemias and lymphomas, afflict older patients who are more prone to the development of GVH disease than are younger persons, and who therefore are not generally considered candidates for allogeneic cell therapy, despite the lack of other curative options. In addition, the immunosuppressive drugs used for GVH disease prophylaxis also increase the risk of secondary infection and increase the relapse rates for certain types of leukemia.
Accordingly, there is a great need to reduce or eliminate the toxicity associated with GVH disease in allogeneic cell therapy protocols while maintaining or increasing the GVT effect in order that the therapy could be utilized to benefit a greater population of patients.
It is an object of this invention to describe an allogeneic cell therapy method that elicits an anti-tumor effect at least as effective as the GVT effect without the associated GVH disease toxicity.
It is an additional object of this invention to describe an allogeneic cell therapy method with reduced treatment related toxicity by eliminating the requirement for a previous allogeneic BMT or chemotherapy conditioning regimen in order to benefit from the therapy.
It is an additional object of this invention to describe a method of allogeneic cell therapy that does not require an HLA-matched donor.